CN101572682A - Method and device for acquiring channel information - Google Patents

Abstract

The invention provides a method and device for acquiring channel information. The method mainly includes: the transmitting end sends downlink pilot information to the receiving end, and receives the mixed pilot returned by the receiving end, the mixed pilot is obtained by multiplying the received downlink pilot by an orthogonal code by the receiving end, Obtained by superimposing with the uplink pilot, the orthogonal code is uniquely corresponding to the receiving end; the transmitting end estimates the uplink channel information according to the uplink pilot information in the mixed pilot, and according to the estimated The uplink channel information and the downlink pilot and orthogonal code information in the mixed pilot are used to estimate the downlink channel information of the receiving end. By using the invention, the transmitting end can correctly acquire the information of the uplink and downlink channels without adding additional feedback signaling overhead.

Description

Method and device for acquiring channel information

technical field

The present invention relates to the field of wireless communication, in particular to a method and device for acquiring channel information.

Background technique

A schematic diagram of a transmission and reception processing process of a wireless communication system is shown in FIG. 1 . In a wireless communication system, the transmitted signal is affected by the physical transmission channel during transmission, and fading and distortion will occur. In order to recover the transmitted signal, the receiving end usually needs to estimate the physical transmission channel and eliminate the physical transmission channel through equalization processing. influence on the transmitted signal. The effect of the above equalization processing is affected by noise. For example, the zero-forcing equalizer will cause noise amplification in the case of a low signal-to-noise ratio, and the MMSE (Minimum Mean Square Error, minimum mean square error) equalizer can effectively suppress the noise. influence, but the variance of the noise needs to be estimated at the receiver.

In order to solve the impact of noise on the above-mentioned equalization processing of the receiving end, the transmitting signal is usually preprocessed according to the characteristics of the physical transmission channel at the transmitting end, that is, the signal is pre-equalized for the SISO (Single Input Single Output) system, For a MIMO (Multiple-Input Multiple-Output, Multiple-Input Multiple-Output) system, the signal is precoded. The above-mentioned preprocessing at the transmitting end can improve signal fading, avoid amplification of noise at the receiving end when processing deep fading channels, and greatly reduce the complexity of signal processing at the receiving end.

The transmitting end needs to know the state information of the downlink channel to preprocess the transmitted signal, which requires the receiving end to estimate the state information of the downlink channel and correctly feed back the state information of the downlink channel to the transmitting end.

In the prior art, the first method in which the receiving end feeds back the state information of the downlink channel to the transmitting end is: the receiving end (such as a terminal) estimates the downlink channel parameters according to the downlink pilot, and calculates the best value for itself based on the downlink channel parameters. An optimal precoding matrix, and then feed back the index number of the optimal precoding matrix, the rank of the downlink channel, and CQI (Channel Quality Indication, Channel Quality Indication) information to the transmitting end, and the transmitting end (such as the base station) feeds back information to precode the transmitted signal.

The disadvantage of the first method in the above-mentioned prior art that the receiving end feeds back the state information of the downlink channel to the transmitting end is that the receiving end needs to perform calculations based on the estimated downlink channel parameters, select the optimal codebook, and increase the calculation of the receiving end. burden. The number of codebooks of the precoding matrix is limited, and there is a quantization error of the codebooks, which will greatly affect the performance of precoding processing at the transmitting end. If it is necessary to ensure that the transmitting end can obtain sufficient downlink channel state information, it will result in huge overhead of uplink feedback signaling.

The second method in the prior art for the receiving end to feed back the state information of the downlink channel to the transmitting end is: a direct channel feedback method. The receiving end (such as a terminal) estimates the downlink channel parameters after receiving the downlink pilot signal, then encodes the estimated downlink channel parameters, and then sends the encoded downlink channel parameters together with the uplink pilot to the base station, wherein The coded downlink channel parameters and uplink pilot are frequency-divided. After receiving the uplink signal, the transmitter (such as the base station) first uses the uplink pilot to estimate the uplink channel parameters, and then uses the estimated uplink channel parameters to recover the downlink channel parameters.

The disadvantage of the second method of the receiving end feeding back the state information of the downlink channel to the transmitting end in the above-mentioned prior art is that the encoded downlink channel parameters need to occupy special time-frequency resources to be fed back to the receiving end.

Contents of the invention

The purpose of the embodiments of the present invention is to provide a method and device for acquiring channel information, so as to solve the problems of increasing the calculation burden of the receiving end and occupying special time-frequency resources in the existing technical solutions.

The purpose of the embodiments of the present invention is achieved through the following technical solutions:

A method for obtaining channel information, comprising:

The transmitting end sends downlink pilot information, and receives the mixed pilot returned by the receiving end. The mixed pilot is obtained by multiplying the received downlink pilot by an orthogonal code at the receiving end, and then superimposing it with the uplink pilot. The orthogonal code is uniquely corresponding to the receiving end;

The transmitting end obtains uplink channel information according to the uplink pilot information in the mixed pilot, and obtains the receiving end's information according to the uplink channel information and the downlink pilot and orthogonal code information in the mixed pilot downlink channel information.

A pilot information processing method, comprising:

receiving downlink pilot information sent by the transmitting end, multiplying the downlink pilot by an orthogonal code, and superimposing it with the uplink pilot to obtain a mixed pilot, the orthogonal code uniquely corresponding to the receiving end;

sending the mixed pilot to the transmitting end.

A device for acquiring channel information, comprising:

The pilot sending and receiving module is used to send downlink pilot information to the receiving end, and receive the mixed pilot returned by the receiving end, the mixed pilot is the receiving end multiplying the received downlink pilot by an orthogonal code After that, it is obtained by superimposing with the uplink pilot, and the orthogonal code is uniquely corresponding to the receiving end;

A channel information acquisition module, configured to acquire uplink channel information according to the uplink pilot information in the mixed pilot, and acquire the uplink channel information according to the uplink channel information and the downlink pilot and orthogonal code information in the mixed pilot. The downlink channel information of the receiver.

A pilot information processing device, comprising:

The mixed pilot acquisition module is used to receive the downlink pilot information sent by the transmitting end, multiply the downlink pilot by an orthogonal code, and then superimpose the uplink pilot to obtain a mixed pilot, the orthogonal code and the The only corresponding to the receiving end;

A mixed pilot transmission module, configured to send the mixed pilot acquired by the mixed pilot acquisition module to the transmitting end.

It can be seen from the above technical solutions provided by the embodiments of the present invention that the embodiments of the present invention can enable the transmitting end (base station) to correctly acquire the information of the uplink and downlink channels without adding additional feedback signaling overhead. Moreover, the processing complexity of the receiving end (terminal) is greatly reduced, which is beneficial to perform pre-equalization or precoding processing on the signal at the transmitting end.

Description of drawings

FIG. 1 is a schematic diagram of a transmission and reception processing process of a wireless communication system;

FIG. 2 is a schematic diagram of the processing process of the base station transmitting data in Embodiment 1 of the present invention;

FIG. 3 is a schematic diagram of a processing process in which a terminal receives and processes a signal in Embodiment 1 of the present invention;

FIG. 4 is a schematic diagram of the processing procedure after the base station receives the data returned by the terminal in Embodiment 1 of the present invention;

FIG. 5 is a schematic structural diagram of an embodiment of an apparatus for obtaining channel information provided by an embodiment of the present invention;

Fig. 6 is a schematic structural diagram of an embodiment of an apparatus for processing pilot information provided by an embodiment of the present invention.

Detailed ways

In the embodiment of the present invention, the transmitting end sends downlink pilot information to the receiving end, and the receiving end multiplies the downlink pilot by an orthogonal code, and then superimposes the uplink pilot to obtain a mixed pilot, and the mixed pilot transmitted to the transmitter. The orthogonal codes uniquely correspond to the receiving end. When there are multiple receiving ends, the orthogonal codes of different receiving ends are orthogonal to each other, and the uplink pilots of different receiving ends are orthogonal to each other.

The transmitting end estimates the uplink channel information according to the uplink pilot information in the mixed pilot, and according to the estimated uplink channel information and the downlink pilot and orthogonal code information in the mixed pilot, the The downlink channel information at the receiving end is estimated.

In practical applications, when the number of uplink pilots at the receiving end is greater than the number of downlink pilots, the receiving end can use multiple uplink pilot resources to repeatedly transmit the mixed pilot signal or encode the downlink pilot Then use multiple uplink pilot resources to transmit the mixed pilot signal. The receiving end can also use the minimum mean square error channel estimation method to estimate the downlink channel at the downlink pilot, multiply the information of the downlink channel by the orthogonal code, and superimpose it with the uplink pilot to obtain the Mixed pilots described above. The receiving end may also transmit the mixed pilot signal to the transmitting end multiple times, each transmission occupies part of the uplink bandwidth, and sends part of the mixed pilot signal respectively.

The above-mentioned downlink pilot and uplink pilot may be composed of multiple sequences, and each sequence occupies a narrowband bandwidth.

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Embodiment 1. In this embodiment, multiple terminals multiplex uplink pilots in a CDM (CODE DIVISION MULTIPLEXING, Code Division Multiplexing) manner, and the uplink pilots of each terminal are orthogonal to each other. The processing process of the base station transmitting data in this embodiment is shown in Figure 2, and the specific processing process is as follows:

The base station first performs code modulation and pre-equalization processing on the signal to be transmitted, inserts downlink pilots in the frequency domain of the processed signal, and then performs OFDM (orthogonal frequency division multiplexing) modulation on the signal, adding CP (Cyclic Prefix, cyclic prefix), it is transmitted through the physical transmission channel.

The processing process of receiving and processing signals by the terminal in this embodiment is shown in FIG. 3 , and the specific processing process is as follows:

The data transmitted by the base station is received by the terminal after being transmitted on the physical transmission channel. Assume that the downlink antenna configuration of the base station is M×N, that is, M is the number of transmitting antennas of the base station, and N is the number of receiving antennas of the terminal. After the terminal de-CPs and OFDM demodulates the received signal, the downlink pilot signal obtained is:

Y _i (k') = H _{dl, i} (k') · P _dl (k') + W _{dl, i} (k')

Y _j (k') = H _{dl, j} (k') · P _dl (k') + W _{dl, j} (k')

The above Y _i (k') is the downlink pilot signal received by the i-th terminal, which is an N×1 matrix, and H _dl,i (k') is the downlink channel matrix from the base station to the i-th terminal, which is N×M matrix, P _dl (k') is the downlink pilot signal, which is an M×1 matrix, k' is the subcarrier sequence number, W _dl,i (k') is the downlink channel noise from the base station to the i-th terminal.

When the terminal uses N transmit antennas, the number of CSI (channel state information) of the downlink channel that needs to be uploaded on each antenna of the terminal is shown in Table 1 below.

Table 1:

Because each downlink pilot symbol of each terminal needs to feed back M×N correlation coefficients, and the terminal needs to feed back the CSI on each receiving antenna, therefore, the resource occupied by the uplink common pilot channel of each terminal is its downlink N times the pilot frequency.

If the STC (space-time coding) method is adopted, it includes the FDM method: N times the common pilot density in the frequency domain; the TDM method: uses N times the OFDM symbols; the CDM method: occupies N common code channels. The same information is fed back on the antenna, and the number of CSIs fed back is M×N.

If the SM (space division multiplexing) method is adopted, N transmit antennas are used, and the number of CSI fed back by each antenna is M.

The terminal multiplies the downlink pilot signal to be fed back by an orthogonal code, and superimposes it on the same time-frequency resource with the uplink pilot signal of the terminal to obtain a mixed pilot signal.

The terminal modulates the above mixed pilot signal together with the uplink data through OFDM, adds the CP and sends it to the base station.

The above downlink pilot and uplink pilot design should meet the following conditions:

1. The convolution of the uplink pilot in the time domain is an impulse function in the range of Lu _ul , that is, the autocorrelation function of the uplink pilot in the time domain is:

$\underset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; a</span>}& \mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}}\end{array}\right.$

2. The convolution of the downlink pilot in the time domain is an impulse function within the range of L _dl , that is, the autocorrelation function of the downlink pilot in the time domain is:

$\underset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; a</span>}& \mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}\end{array}\right.$

3. The convolution of the downlink pilot and the uplink pilot in the time domain is zero within the range of L _ul + L _dl , that is:

$\underset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,0</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}}$

The uplink and downlink pilot designs satisfying the above conditions can prevent the uplink and downlink channels from interfering with each other when the base station estimates the uplink and downlink channels. In specific implementation, the above conditions can be met through the following operations:

1. The downlink pilot and the uplink pilot are orthogonal to each other. The uplink pilot sequence is a cyclic shift of the downlink pilot sequence, and the length of the cyclic shift is greater than the maximum channel delay extension.

2. The downlink pilot and the uplink pilot are orthogonal to each other. The downlink pilot and the uplink pilot are respectively spread with different orthogonal codes and then superimposed to obtain a mixed pilot.

3. The downlink pilot is spread with an orthogonal code and then superimposed on the uplink pilot to obtain a mixed pilot. Although the uplink and downlink pilots of this method do not meet the above conditions, as long as the spreading factor is large enough and the design makes the mean value of the uplink pilots zero, it is approximately considered that the impact of the uplink pilots on downlink channel estimation is almost negligible.

When there are multiple terminals, the orthogonal codes of different terminals are orthogonal to each other. Therefore, the orthogonal code can be used to distinguish downlink pilot signals of different terminals. The method for the orthogonal codes of different terminals to be orthogonal to each other can be as follows:

The orthogonal codes corresponding to the other terminals are cyclic shifts of the orthogonal codes corresponding to the terminal, and the length of the cyclic shift is greater than the maximum channel delay extension; or, the orthogonal codes corresponding to the other terminals are the orthogonal codes corresponding to the terminal The codes are different spreading codes.

When there are multiple terminals, uplink pilots of different terminals are also orthogonal to each other. The method for the uplink pilots of different terminals to be orthogonal to each other can be as follows:

The uplink pilot sequences of other terminals are cyclic shifts of the uplink pilot sequences of the terminal, and the length of the cyclic shift is greater than the maximum channel delay extension; or, the uplink pilots of different terminals are respectively performed with different orthogonal codes spread spectrum.

The above-mentioned orthogonal codes may be Walsh codes, CAZAC codes and the like.

For simplicity, we assume that the number of base station transmit antennas, the number of receive antennas, the number of terminal transmit antennas, and the number of receive antennas are all 1, that is, the SISO system. The following formula can be easily extended to the MIMO system, and the principle is the same.

The processing process after the base station in this embodiment receives the data returned by the terminal is shown in Figure 4, and the specific processing process is as follows:

The signal sent by the terminal is received by the base station after being transmitted on the uplink channel. After the base station de-CPs and OFDM demodulates the received signal, the obtained mixed pilot signal is:

Y _BS (k) = H _{ul, i} (k) · (Y _i (k') · C _{ul, i} (k) + P _{ul, i} (k)) + W _{ul, i} (k) + H _{ul, j} (k) (Y _j (k′) C _{ul, j} (k) + P _{ul, j} (k)) + W _{ul, j} (k)

=H _{ul, i} (k) H _{dl, i} (k') P _dl (k') C _{ul, i} (k) + H _{ul, i} (k) P _{ul, i} (k) + W _i (k)+

H _{ul, j} (k) H _{dl, j} (k′) P _dl (k′) C _{ul, j} (k)+H _{ul, j} (k) P _{ul, j} (k)+W _j (k)

W _i (k) = H _{ul, i} (k) · W _{dl, i} (k') · C _{ul, i} (k) + W _{ul, i} (k)

W _j (k) = H _{ul, j} (k) · W _{dl, j} (k') · C _{ul, j} (k) + W _{ul, j} (k)

Among them, Y _BS (k) is the superposition signal of mixed pilot signals returned by multiple terminals received by the base station, H _ul,i (k) is the uplink channel from the i-th terminal to the base station, and P _ul,i (k) is The uplink pilot frequency of the i-th terminal, C _ul,i (k), is the orthogonal code used by the i-th terminal to distinguish different users. W _ul,i (k) is the uplink channel noise from the ith terminal to the base station.

The base station first estimates the uplink channel, and multiplies Y _BS (k) in the frequency domain by the conjugate of the uplink pilot:

Z _{ul, i} (k) = Y _BS (k) P ^* _{ul, i} (k)

=H _ul,i (k)·H _dl,i (k')·P _dl (k')·C _ul,i (k)·P ^* _ul,i (k)+H _ul,i (k)· P _{ul, i} (k) · P ^* _{ul, i} (k) + W _i (k) · P ^* _{ul, i} (k) +

H _{ul, j} (k) H _{dl, j} (k′) P _dl (k′) C _{ul, j} (k) P ^* _{ul, i} (k)+H _{ul, j} (k) P _ul,j (k) P ^* _ul,i (k)+W _j (k)P ^* _ul,i (k)

Since the uplink and downlink pilot signals of each terminal meet the above conditions, the estimation of the uplink channel is not affected by pilot aliasing. The uplink channel of the i-th terminal estimated by the base station is:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

$<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&CenterDot;</span>{{\mathrm{<span\; class="notranslate">\; P</span>}}^{<span\; class="notranslate">\; *</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

Then, the base station estimates the downlink channel based on the estimation result of the uplink channel, and multiplies the conjugate of the downlink pilot by Y _BS (k) in the frequency domain:

Z _dl (k) = Y _BS (k) · P ^* _dl (k')

=H _ul,i (k)·H _dl,i (k')·P _dl (k')·C _ul,i (k)·P ^* _dl (k')+H _ul,i (k)·P _{ul, i} (k) P ^* _dl (k′)+W _i (k) P ^* _dl (k′)+

H _{ul, j} (k) H _{dl, j} (k′) P _dl (k′) C _{ul, j} (k) P ^* _dl (k′) + H _{ul, j} (k) P _{ul , j} (k) · P ^* _dl (k′) + W _j (k) · P ^* _dl (k′)

Because the uplink and downlink pilot signals of each terminal meet the above conditions, the estimation of the downlink channel is not affected by pilot aliasing:

${\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&Center\; Dot;</span>{{\mathrm{<span\; class="notranslate">\; P</span>}}^{<span\; class="notranslate">\; *</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span>$

Because the downlink channels of different users are distinguished by uplink orthogonal codes, the downlink channel of the i-th terminal estimated by the base station is:

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; dl</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; *</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}$

$<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&Center\; Dot;</span>{{\mathrm{<span\; class="notranslate">\; P</span>}}^{<span\; class="notranslate">\; *</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{{\mathrm{<span\; class="notranslate">\; C</span>}}^{<span\; class="notranslate">\; *</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; dl</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; ul</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}$

In practical applications, some improvements can be made to the estimation process of the above-mentioned uplink channel and downlink channel as follows.

1. MMSE channel estimation suppresses noise.

It can be seen from the above derivation formulas of the uplink channel and downlink channel of the terminal that when estimating the uplink channel and the downlink channel, the noise includes: uplink channel noise and downlink channel noise. Therefore, the terminal can use the MMSE (Minimum Mean Square Error) channel estimation method to estimate the downlink channel at the downlink pilot after receiving the downlink pilot signal sent by the base station. The MMSE channel estimation method can effectively Suppress downlink channel noise.

The downlink pilot signal received by the terminal:

Y _i (k') = H _{dl, i} (k') · P _dl (k') + W _{dl, i} (k')

Use the MMSE channel to estimate the downlink channel at the downlink pilot:

Z _i (k) = Y _i (k) P ^* _dl (k')/|P _dl (k')| ² = H _dl,i (k')+W _dl,i (k') P ^* _dl (k′)/|P _dl (k′)| ²

${\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}}_{\mathrm{<span\; class="notranslate">\; dl</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; zz</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; en</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; zz</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$ ${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; en</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

Then, the terminal multiplies the estimated downlink channel information at the downlink pilot by an orthogonal code, superimposes it on the uplink pilot, and sends it to the base station. The improved method can improve the estimation performance of uplink channel and downlink channel.

2. Compression coding.

In order to reduce the CSI feedback amount of the terminal and reduce the resources occupied by the uplink common pilot of the terminal, the terminal can compress and encode the downlink channel information at the downlink pilot that needs to be fed back, multiply it by an orthogonal code, and superimpose it on the uplink pilot. frequency.

3. Repeat transmission.

In order to improve the estimation performance of the uplink channel and downlink channel, if the number of uplink pilots of the terminal is greater than the number of downlink pilots, multiple uplink pilot resources can be used to repeatedly transmit the above mixed pilot signals, or the downlink pilots can be coded and then multiple Uplink pilot resource transmission, so as to ensure that the mixed pilot signal is correctly received by the base station.

4. Some CSI feedback.

When the terminal transmits the mixed pilot signal to the base station, it may first occupy a part of the bandwidth and transmit a part of the mixed pilot signal. Then, after a period of time, another part of the bandwidth is occupied, and then a part of the mixed pilot signal is transmitted, that is, the mixed pilot signal is transmitted to the base station by means of frequency hopping, and the narrowband downlink pilot can also be transmitted by frequency hopping in the downlink.

Embodiment 2, this embodiment is mainly to reduce the destruction of pilot orthogonality due to frequency selective fading. When the bandwidth is greater than the coherent bandwidth, different frequency points present different fading characteristics after the signal experiences the broadband wireless physical channel, so that Each part of the signal experiences different attenuation, causing frequency selective fading.

A process for estimating the uplink channel and the downlink channel provided by this embodiment is as follows:

1. The base station generates downlink pilots, performs Fourier transform processing on the downlink pilots, and then performs subcarrier mapping and IFFT transformation processing, and then transmits them after OFDM modulation and CP addition.

2. The downlink pilot sent by the above base station is received by the terminal. After removing CP and OFDM demodulation, the terminal multiplies the obtained downlink pilot by an orthogonal code, and superimposes it with the uplink pilot processed by Fourier transform. The mixed pilot is obtained, and the terminal transmits the mixed pilot to the base station.

3. The base station receives the above-mentioned mixed pilot, and performs FFT transformation, de-subcarrier mapping, and inverse Fourier transform on the mixed pilot. Then, in the time domain, the uplink pilot is firstly used to estimate the uplink channel. Since the uplink and downlink pilots meet the orthogonal condition in the time domain (one or several OFDM symbols are approximately constant in the channel), the uplink channel Estimates are immune to pilot aliasing and frequency selectivity.

4. The base station estimates the downlink channel according to the estimated uplink channel information, the downlink pilot to be transmitted and the above mixed pilot.

Embodiment 3, this embodiment is mainly to reduce the destruction of pilot orthogonality caused by different uplink and downlink scrambling codes. A process for estimating the uplink channel and the downlink channel provided by this embodiment is as follows:

1. The base station generates downlink pilots, performs Fourier transform processing on the downlink pilots, and then performs subcarrier mapping and IFFT transformation processing. Then, after OFDM modulation, adding CP, scrambling with downlink user scrambling codes, and then transmitting go out.

2. The downlink pilot sent by the above base station is received by the terminal, and the terminal descrambles the downlink scrambling code, removes CP, OFDM demodulates the downlink pilot, scrambles with the uplink user scrambling code, and multiplies it by an orthogonal code , is superimposed with the uplink pilot processed by the Fourier transform to obtain a mixed pilot, and the terminal transmits the mixed pilot to the base station.

3. The base station receives the above-mentioned mixed pilot, and performs FFT transformation, de-subcarrier mapping, and inverse Fourier transform processing on the mixed pilot. Then, in the time domain, the uplink pilot is firstly used to estimate the uplink channel. Since the uplink and downlink pilots meet the orthogonal condition in the time domain (one or several OFDM symbols are approximately constant in the channel), the uplink channel Estimates are not affected by pilot aliasing.

4. The base station estimates the downlink channel according to the estimated uplink channel information, the downlink pilot to be transmitted and the above mixed pilot.

Embodiment 4, this embodiment is mainly to reduce the influence of noise variance and frequency selective fading, a kind of processing procedure that this embodiment provides for estimating uplink channel and downlink channel is as follows:

1. The base station generates downlink pilots, performs N-fold narrowband spread spectrum processing on each downlink pilot, and then transmits them after OFDM modulation and CP addition. It is also possible to repeat the N times spread signal multiple times.

2. The downlink pilot sent by the above base station is received by the terminal, and the terminal de-CPs and OFDM demodulates the downlink pilot, first estimates the channel at the downlink pilot, and then despreads the channel to obtain the despread The channel is then spread with a spreading code. Afterwards, it is multiplied by an orthogonal code and superimposed with the uplink pilot to obtain a mixed pilot, and the terminal transmits the mixed pilot to the base station.

3. After the base station receives the mixed pilot, it performs despreading processing and uses the uplink pilot to estimate the uplink channel. Since the uplink and downlink pilots meet the orthogonal condition, the estimation of the uplink channel is not affected by pilot aliasing. Influence.

4. The base station estimates the downlink channel according to the downlink pilot that starts to transmit and the mixed pilot.

The above despreading operation can reduce the downlink noise variance to the original 1/sqrt(N), and can effectively resist frequency selective fading. Because the terminal performs the uplink spread spectrum operation, even if the terminal allocates very low power to the received downlink pilot signal, the base station can still estimate the information of the downlink channel well.

Embodiment 5, this embodiment is mainly to reduce the impact of frequency selective fading, a processing procedure for estimating the uplink channel and downlink channel provided by this embodiment is as follows:

1. The base station generates a downlink pilot, and then transmits it after OFDM modulation and CP addition. The downlink pilot is composed of a plurality of sequences, each sequence occupies a narrowband bandwidth, and the uplink and downlink pilots contain the same number of sequences, and are orthogonal to each other;

2. The downlink pilot sent by the above-mentioned base station is received by the terminal, and the terminal de-CPs and OFDM demodulates the downlink pilot, first estimates the channel at the downlink pilot, and then multiplies it by an orthogonal code and compares it with the uplink After the pilots are superimposed, a mixed pilot is obtained, and the terminal transmits the mixed pilot to the base station. The uplink and downlink pilots are composed of a plurality of sequences, each sequence occupies a narrowband bandwidth, and the uplink and downlink pilots contain the same number of sequences, and are orthogonal to each other;

3. After receiving the mixed pilot, the base station uses the uplink pilot to estimate the uplink channel. Since the uplink and downlink pilots satisfy the orthogonal condition, the estimation of the uplink channel is not affected by pilot aliasing.

4. The base station estimates the downlink channel according to the downlink pilot that starts to transmit and the mixed pilot.

The four improved methods in the above-mentioned embodiment 1 are also applicable to the embodiments 2-5, and the four improved methods can be used in combination, and the embodiments 1-5 can also be used in combination.

The structural diagram of an embodiment of the channel information acquisition device provided by the embodiment of the present invention is shown in Figure 5, including the following modules:

The pilot sending and receiving module 51 is configured to send downlink pilot information to the receiving end, and receive the mixed pilot returned by the receiving end, and the receiving end of the mixed pilot multiplies the received downlink pilot by an orthogonal code After that, it is obtained by superimposing the uplink pilot frequency orthogonal to the downlink pilot frequency, and the orthogonal code uniquely corresponds to the receiving end. It includes: a Fourier transform processing module 511 , a scrambling code processing module 512 , a spectrum spreading processing module 513 or a segment transmission module 514 .

The channel information acquisition module 52 is configured to estimate the uplink channel information according to the uplink pilot information in the mixed pilot, and according to the estimated uplink pilot information and the downlink pilot in the mixed pilot and the orthogonal The code information is used to estimate the downlink channel information of the receiving end.

Wherein, the Fourier transform processing module 511 in the above-mentioned pilot sending and receiving module 51 is used to perform Fourier transform on the downlink pilot and then transmit it, receive the mixed pilot returned by the receiving end, and use the Inverse Fourier transform is performed on the mixed pilot, where the mixed pilot is obtained by the receiving end after multiplying the downlink pilot by the orthogonal code and superimposing it with the Fourier-transformed uplink pilot;

Wherein, the scrambling code processing module 512 in the above-mentioned pilot frequency sending and receiving module 51 is used to scramble the downlink pilot frequency with the downlink user scrambling code and then transmit it, receive the mixed pilot frequency returned by the receiving end, and Descrambling the uplink scrambling of the mixed pilot, descrambling the downlink scrambling of the downlink pilot for the receiving end, performing scrambling with the scrambling code of the uplink user, multiplying the orthogonal code by the mixed pilot, and then combining with Obtained after uplink pilots are superimposed;

Wherein, the spread spectrum processing module 513 in the above-mentioned pilot sending and receiving module 51 is used to transmit the downlink pilot after performing spread spectrum processing, receive the mixed pilot returned by the receiving end, and send the mixed pilot Perform despreading processing, the mixed pilot frequency is the receiving end performing despreading processing on the downlink pilot frequency, and then performing spreading processing on the downlink pilot frequency with a spreading code and multiplying by the orthogonal code , and then obtained by superimposing with the uplink pilot frequency.

Wherein, the segment transmission module 514 in the above-mentioned pilot transmission and reception module 51 is used to transmit the downlink pilot to the receiving end in multiple times, and each transmission occupies part of the downlink bandwidth respectively, and transmits part of the downlink bandwidth respectively. downlink pilot.

The above-mentioned channel information acquisition device may be a base station, and the above-mentioned Fourier transform processing module 511, scrambling code processing module 512, spread spectrum processing module 513 or segment transmission module 514 may also be combined and used simultaneously.

A schematic structural diagram of an embodiment of a pilot information processing device provided in an embodiment of the present invention is shown in Figure 6, including the following modules:

The mixed pilot acquisition module 61 is configured to receive the downlink pilot information sent by the transmitting end, multiply the downlink pilot by an orthogonal code, and then superimpose it with the uplink pilot to obtain a mixed pilot, the orthogonal code and The receiving end is uniquely corresponding. It includes: a compression encoding module 611 or a minimum mean square error channel estimation module 612 .

The mixed pilot transmission module 62 is configured to transmit the mixed pilot acquired by the mixed pilot acquisition module 61 to the transmitting end. Including: at least one of a repeat transmission module 621 and a segment transmission module 622.

Wherein, the compression encoding module 611 in the mixed pilot acquisition module 61 is configured to perform compression encoding on the downlink pilot, multiply by the orthogonal code, and superpose with the uplink pilot to obtain the mixed pilot;

Wherein, the minimum mean square error channel estimation module 612 in the above-mentioned hybrid pilot acquisition module 61 is used to estimate the downlink channel of the downlink pilot by using the minimum mean square error channel estimation method, and multiply the information of the downlink channel by The mixed pilot is obtained after superimposing the orthogonal code with the uplink pilot. It includes: a repeated transmission module 621 or a segmented transmission module 622 .

Wherein, the repeated transmission module 621 in the above-mentioned mixed pilot transmission module 62 is used to use multiple uplink pilot resources to repeatedly transmit the A mixed pilot signal, or, after encoding the downlink pilot, use multiple uplink pilot resources to transmit the mixed pilot signal;

Wherein, the segmented transmission module 622 in the above-mentioned mixed pilot transmission module 62 is used to transmit the mixed pilot signal to the transmitting end in multiple times, and each transmission occupies part of the uplink bandwidth respectively, and sends part of the described Mixed pilot signal.

The foregoing pilot information processing apparatus may be a terminal. The compression encoding module 611, the minimum mean square error channel estimation module 612, the repeated transmission module 621 and the segmented transmission module 622 may also be combined and used simultaneously.

To sum up, by using the method and device described in the embodiments of the present invention, the base station can correctly obtain the information of the uplink and downlink channels without additionally opening up precious time-frequency resources for the uplink channel. In addition, the terminal does not need to judge the precoding matrix, which greatly reduces the processing complexity of the terminal. It can also avoid damage to pilot orthogonality caused by frequency selective fading, and avoid damage to pilot orthogonality caused by different scrambling codes for uplink and downlink. The base station can implement more flexible scheduling and improve system capacity based on the obtained complete downlink channel state information.

The method and device described in the embodiments of the present invention may be applicable to SISO systems and MIMO systems. The base station can perform pre-equalization processing or pre-coding processing according to the acquired channel information, and can flexibly design the pre-coding matrix, avoiding the decrease in accuracy caused by the limited number of codebooks. It is also beneficial for the base station to flexibly allocate time-frequency resources to different services according to channel information.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (20)

1. A method for obtaining channel information, comprising: The transmitting end sends downlink pilot information, and receives the mixed pilot returned by the receiving end. The mixed pilot is obtained by multiplying the received downlink pilot by an orthogonal code at the receiving end, and then superimposing it with the uplink pilot. The orthogonal code is uniquely corresponding to the receiving end; The transmitting end obtains uplink channel information according to the uplink pilot information in the mixed pilot, and obtains the receiving end's information according to the uplink channel information and the downlink pilot and orthogonal code information in the mixed pilot downlink channel information. 2. The method according to claim 1, wherein the transmitting end sends downlink pilot information, and receives the mixed pilot returned by the receiving end, specifically comprising: The transmitting end performs Fourier transform processing on the downlink pilot, sends it out, and receives the mixed pilot returned by the receiving end, and the mixed pilot is the Fourier transform processed by the receiving end After the downlink pilot frequency is multiplied by the orthogonal code, it is obtained by superimposing it with the uplink pilot frequency after Fourier transform. 3. The method according to claim 1, wherein the transmitting end sends downlink pilot information, and receives the mixed pilot returned by the receiving end, specifically comprising: The transmitting end performs spread spectrum processing on the downlink pilot, sends it out, and receives the mixed pilot returned by the receiving end, and the mixed pilot is the downlink pilot after the spreading process by the receiving end After the despreading process is performed, the downlink pilot after the despreading process is spread with different spreading codes, multiplied by the orthogonal code, and superimposed with the uplink pilot to obtain, the The transmitting end performs despreading processing on the mixed pilot. 4. The method according to claim 3, characterized in that said performing spread spectrum processing on said downlink pilot specifically comprises: The downlink pilot is narrow-band spread near the subcarrier where it is located, and this operation is repeated on the entire bandwidth to generate the downlink pilot after spreading. 5. The method according to claim 1, wherein the transmitting end sends downlink pilot information, and receives the mixed pilot returned by the receiving end, specifically comprising: The transmitting end scrambles the downlink pilot with a downlink user scrambling code and transmits it, and receives the mixed pilot returned by the receiving end, and the mixed pilot decodes the downlink pilot for the receiving end The downlink scrambling code is multiplied by the orthogonal code after being scrambled by the uplink user scrambling code, and then superimposed with the uplink pilot frequency to obtain the uplink scrambling code. The transmitting end decomposes the uplink scrambling code on the mixed pilot frequency. 6. The method according to claim 1, wherein the sending of the downlink pilot information by the transmitting end specifically comprises: The transmitting end sends the downlink pilot frequency multiple times, and each transmission occupies part of the downlink bandwidth, and sends part of the downlink pilot frequency respectively. 7. A pilot information processing method, comprising: receiving downlink pilot information sent by the transmitting end, multiplying the downlink pilot by an orthogonal code, and superimposing it with the uplink pilot to obtain a mixed pilot, the orthogonal code uniquely corresponding to the receiving end; sending the mixed pilot to the transmitting end. 8. The method according to claim 7, wherein the downlink pilot and the uplink pilot are orthogonal to each other. 9. The method according to claim 8, wherein the uplink pilot sequence is a cyclic shift of the downlink pilot sequence, and the length of the cyclic shift is greater than the maximum channel delay extension. 10. The method according to claim 8, after multiplying the downlink pilot by an orthogonal code, and then superimposing it with the uplink pilot to obtain a mixed pilot, specifically comprising: The downlink pilot and the uplink pilot are respectively spread with different orthogonal codes, and then superimposed to obtain a mixed pilot. 11. The method according to claim 7, characterized in that, after multiplying the downlink pilot by an orthogonal code, and then superimposing it with the uplink pilot to obtain a mixed pilot, specifically comprising: After the downlink pilot is spread with an orthogonal code, it is superimposed on the uplink pilot to obtain a mixed pilot. 12. The method according to claim 7, wherein when there are multiple receivers, the orthogonal codes corresponding to different receivers are orthogonal to each other, and the uplink pilots of different receivers are orthogonal to each other. 13. The method according to claim 12, wherein the orthogonal codes corresponding to different receiving ends are orthogonal to each other, specifically comprising: The orthogonal codes corresponding to different receiving ends constitute a cyclic shift with each other, and the length of the cyclic shift is greater than the maximum channel delay extension; or, The orthogonal codes corresponding to different receiving ends are different spreading codes respectively. 14. The method according to claim 12, the uplink pilots of different receiving ends are orthogonal to each other, specifically comprising: The uplink pilot sequences of different receiving ends form a cyclic shift with each other, and the length of the cyclic shift is greater than the maximum channel delay extension; or, The uplink pilots of different receivers are spread with different orthogonal codes respectively. 15. The method according to any one of claims 7 to 14, wherein the sending the mixed pilot to the transmitting end specifically comprises: The receiving end uses multiple uplink pilot resources to repeatedly transmit the mixed pilot signal, and the number of uplink pilots at the receiving end is greater than the number of downlink pilots; or, The receiving end encodes the downlink pilot and uses multiple uplink pilot resources to transmit the mixed pilot signal, and the number of uplink pilots at the receiving end is greater than the number of downlink pilots; or, The receiving end sends the mixed pilot signal to the transmitting end multiple times, each sending takes part of the uplink bandwidth, and sends part of the mixed pilot signal respectively. 16. A device for acquiring channel information, comprising: The pilot sending and receiving module is used to send downlink pilot information to the receiving end, and receive the mixed pilot returned by the receiving end, the mixed pilot is the receiving end multiplying the received downlink pilot by an orthogonal code After that, it is obtained by superimposing with the uplink pilot, and the orthogonal code is uniquely corresponding to the receiving end; A channel information acquisition module, configured to acquire uplink channel information according to the uplink pilot information in the mixed pilot, and acquire the uplink channel information according to the uplink channel information and the downlink pilot and orthogonal code information in the mixed pilot. The downlink channel information of the receiver. 17. The channel information acquisition device according to claim 16, wherein the pilot transmission and reception module comprises: a Fourier transform processing module, a scrambling code processing module, a spread spectrum processing module or a segmented transmission module, in, The Fourier transform processing module is used to perform Fourier transform processing on the downlink pilot, send it out, receive the mixed pilot returned by the receiving end, and perform inverse Fourier transform on the mixed pilot, the The mixed pilot is obtained by the receiving end after multiplying the Fourier-transformed downlink pilot by the orthogonal code, and superimposing it with the Fourier-transformed uplink pilot; The scrambling code processing module is used to scramble the downlink pilot with a downlink user scrambling code and then transmit it, receive the mixed pilot returned by the receiving end, and descramble the mixed pilot, and the mixed pilot The frequency is obtained by the receiving end descrambling the downlink pilot, performing scrambling with the uplink user scrambling code, multiplying by the orthogonal code, and superimposing the uplink pilot; The spread spectrum processing module is used to perform spread spectrum processing on the downlink pilot, send it out, receive the mixed pilot returned by the receiving end, and perform despreading processing on the mixed pilot, which is the mixed pilot The receiving end performs despreading processing on the downlink pilots after the spread spectrum processing, and then uses different spreading codes to perform spread spectrum processing on the downlink pilots after the despreading processing, and then multiplies them by the orthogonal code, and obtained after superposition with the uplink pilot; A segmented transmission module, configured to transmit the downlink pilot to the receiving end multiple times, each transmission occupies a part of the downlink bandwidth, and sends part of the downlink pilot respectively. 18. A pilot information processing device, comprising: The mixed pilot acquisition module is used to receive the downlink pilot information sent by the transmitting end, multiply the downlink pilot by an orthogonal code, and then superimpose the uplink pilot to obtain a mixed pilot, the orthogonal code and the The only corresponding to the receiving end; A mixed pilot transmission module, configured to send the mixed pilot acquired by the mixed pilot acquisition module to the transmitting end. 19. The pilot information processing device according to claim 18, wherein the hybrid pilot acquisition module comprises: a compression coding module or a minimum mean square error channel estimation module, wherein, A compression encoding module, configured to compress and encode the downlink pilot, multiply by the orthogonal code, and superimpose with the uplink pilot to obtain the mixed pilot; The minimum mean square error channel estimation module is used to estimate the downlink channel of the downlink pilot by using the minimum mean square error channel estimation method, multiply the information of the downlink channel by the orthogonal code, and combine it with the uplink pilot The mixed pilot is obtained after superposition. 20. The pilot information processing device according to claim 18 or 19, wherein the mixed pilot transmission module comprises: a repeated transmission module or a segmented transmission module, wherein, A repeated transmission module, configured to use multiple uplink pilot resources to repeatedly transmit the mixed pilot signal to the transmitting end when the number of uplink pilots at the receiving end is greater than the number of downlink pilots, or transmit the mixed pilot signal to the transmitting end, or transmit the mixed pilot signal to the transmitting end transmit the mixed pilot signal with a plurality of uplink pilot resources after encoding the frequency; The segmented transmission module is configured to transmit the mixed pilot signal to the transmitting end in multiple times, each transmission occupies part of the uplink bandwidth, and sends part of the mixed pilot signal respectively.

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